Washington, DC (AP) – Justice Department officials are conducting a sweeping review of more than 1,000 grand jury presentations made by Illinois prosecutors following the dismissal of a high-profile case over misconduct, the top federal prosecutor for Chicago said on Wednesday.

Andrew Boutros, the U.S attorney for the Northern District of Illinois, said the massive review will include all pending grand jury proceedings in his district as well as other presentations by prosecutors going back almost 20 years. It was sparked by revelations of grand jury misconduct that forced prosecutors to abandon a closely watched case against four activists who protested outside a federal building during last year’s immigration crackdown in the city.

“It’s going to be a massive review, a comprehensive review and it is underway,” said Boutros, who was in Washington for an unrelated news conference. Boutros said the process is meant to ensure that his prosecutors have “acted ethically” and to provide “assurances and confidence” that other pending cases have not been tainted by similar issues.

The Justice Department dropped charges against the activists in May after a judge scrutinized allegations of misconduct, which included a prosecutor meeting with a grand juror outside proceedings and other jurors who disagreed with the case being dismissed from participating.

When the case was dismissed, Boutros told a judge that the conduct was upsetting, adding that: “No one acted with the intent to mislead, your honor.”

The judge overseeing the case took the extraordinary step last month of releasing the transcripts of the presentation made by prosecutors, who were seeking to secure an indictment against the activists in the most high-profile cases to come out of the crackdown that rippled across the nation’s third-largest city and its suburbs last year.

The transcripts showed that one of the grand jurors called the case a “crock of (expletive).” The grand juror was subsequently excused from the proceedings.